Fuse link



L. PUMMER Jan. 5, 1954 FUSE LINK Filed Jan. 2, 1952 Patented Jan. 5, 1954 2, 55,350. FUsE LINK Leo Bummer, Chicago,

Electric Company; ration of Delaware 111., assignor to McGraw Milwaukee, 'Wis., 11 corpo- ApplicationJanuary 2, 1952, Serial No. 264,488 3-Claims. (Cl. 200-135) This invention relates to an fuse link.

One of the problems at the present time in the manufacture of high quality. fuse links having heavy tin sections, is to center the tin so that it will enter the tube or cartridge freely. Another problem is that high amperage links tend tomelt oif from the lower leader instead of the tin melt ing inthe middle. of the tin section as was intended. It is also a problem to solder a tin'fusible section to copper parts without overheating the tin and causing it to nick down to a smaller cross-sectional area adjacent to the copper parts. Anything that can be done to eliminate these problems will facilitate the manufacture of fuses and greatly increase the quality of the product.

It is to overcome these problems and also to provide better fuse characteristics that I devised this improved design for fuse links.

One of the objects of my invention is to construct a fuse link in which the fusible tin section is located symmetrically with the axis of the link and of the cartridge.

Another object is to provide a fuse link in which a slot for the tin section is so constructed as to facilitate the feeding of solder to attach the tin section.

Still another object is to provide a means of attaching the tin to the copper so as to give improvement in a better heat and current transfer between the two parts.

And another object is to provide a strain wire in a fuse link whereby the stress is evenly distributed.

I illustrate my novel idea in the accompanying drawing in which Fig. 1 is an elevation of a fuse link embodying my invention with part of the tubes broken away.

Fig. 2 is a fragmentary view partly in section taken approximately on the line 2-2 of Fig. 1.

Fig. 3 is a section taken on the line 3-3 of Fig. 1.

Fig. is a section taken on the line 4-4 of Fig. 2.

Like reference characters indicate like parts throughout.

The fuse link illustrated in Fig. 1 comprises a terminal head I with a button 2 extending downwardly and having a slot 3 extending upwardly from the lower face 2a. A leader 4 has its end portion tightly encompassed in a sleeve member 5 which has a ferrule member 6 extending upwardly. From the upper face 50. of this ferrule t is a slot 3 extending downwardly. The faces 2a and ta are spaced apart and between them is a fusible element 8 of some low melting material 'suchas tin. This element 8 is a thin flat strip and its upper end fits into the slot 3 g and its lower end fits into the slot '1.

Referring to 2', after the fusible element 8 is located in the slots 3 and I a small hole 9 is drilled transversely'through the tubular portion of the button 2' and through that part of the element 8 in line with the transverse hole 9 that extends into the slot {making a hole H). Another small hole I l is drilled transversely through the tubular portion of the ferrule 6 and through the lower part of the element 8 that extends into the slot 7 in line with the transverse hole ll making a hole l2. f

A strain wire is threadedthrough the holes 9 in the button 2 and the hole ID of the fusible element 3 down to the lower segment of the fuse link and through the hole I I of the ferrule 6 and the hole l2 of the element 8 and up again along the side of the fuse link to meet the beginning of the strain wire and the wire ends are then fastened together. This strain wire I3 is tightened to form a taut connection between the terminals, parallel with the fusible element, and serves to distribute evenly the tension between the two terminals.

A low melting solder [4 such as pure tin is injected into the slot and the drilled hole of both terminals to make a firm bond between the fusible element and the terminals and between the strain wire and the terminals. Feeding solder into slots and holes is a fairly simple operation and can be done quickly and accurately on the average production line.

This slot design for a fuse link provides improved heat transfer because the fusible element is soldered on both faces to the terminal instead of only on one face as in the conventional construction. This provides greater conducting area over the joints for the electric current and results in more uniform time-current characteristic. Improved heat transfer at the joints prevents melting at the joints during high amperage flow, and thus the melting takes place in the middle of the fusible element which is the preferred place for optimum quality.

Thus it can be seen that with my novel form of fuse links many manufacturing problems can be eliminated. Locating the tin fusible section in the terminals is facilitated. The soldering can be handled with greater skill and the joints provide better heat transfer. By solving these problems the number of shop rejections can be reduced which means less waste and more production while increasing the quality of the links.

I claim:

1. A high voltage fuse link having spaced terminal sections, the opposing faces of each terminal having slots extending upwardly and downwardly from respective opposing faces, a low melting element extending between the said opposing faces, the ends of the low melting element extending into the said slots of said opposing faces, a small hole extending transversely through each terminal and the end of the element that extends into the slot, a strain wire threaded through both transverse holes and fastened in taut position, a low melting solder injected into the slots on both sides of the ends of the element,

and into the transverse hole through each terminal, the low melting solder forming a firm joint for the smooth flow of current between the terminals and a flexible leader attached to the lower terminal whereby the entire link is placed in tension when assembled in a fuse tube and the stresses do not affect the fusible element of said link.

2. A high voltage fuse link having terminal sections spaced apart, alow melting element extending between the two terminals with the ends of said element extending into slots on opposing faces of said terminals, a transverse opening through each of the terminals and the ends of said fusible element, a strain wire threaded through said transverse opening, and fastened tautly on opposite sides of the terminal across the space between the terminals, a low melting solder poured into the slots fastening both faces of the fusible element ends to the sides of the slots and 4 into the transverse openings in both terminals to fasten the strain wire to the terminals and a flexible leader attached to the lower terminal whereby the entire link is placed in tension when assembled in a fuse tube and the stresses do not affect the fusible element of said link.

3. A high voltage fuse link comprising two terminal portions spaced apart, slots extending parallel with the axis of said terminals inwardly from the opposing faces of said terminals, a low melting fusible element extending between the faces'and into the slots of said opposing terminal faces, a transverse hole through said terminals and the ends of said fusible element, a strain wire threaded through said holes and extending tautly between said terminals on opposite sides thereof to distribute the stress evenly, a low melting solder injected into said holes to bond the strain wire to the terminals and into the slots to bond the faces of said element to both sides of said slots, the joint thus formed resulting in uniform time current characteristics and a flexible leader attached to the lower terminal whereby the entire link is placed in tension when assembled in a fuse tube and the stresses do not affect the fusible element of said link.

LEO PUMMER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,379,114 McDonald May 24, 1921 2,485,076 Timerman Oct. 18, 1949 2,537,827 Heath Jan. 9, 1951 

